Paint spray booths often form part of a production line for the manufacture of products such as car bodies. Fully assembled or partly completed car bodies are usually conveyed by a conveyor into a room or tunnel forming the enclosure part of the booth and a desired color or colors is or are applied by spraying paint onto the bodies either manually or automatically. In manual spraying suitably clad personnel or operators working in the booth direct paint spray equipment towards the bodies which are to be painted; gases and fumes as well as paint sprays and mists, are released during the spraying operation and these are injurious to health. An effective ventilation system both for the personnel and for the effective operation of the booth is thus required.
It is also often desirable to be able to apply different colors or shades to different products passing through a booth. Therefore cross-contamination of colors should be avoided by preventing paint drifting from one spray station to another within the booth.
Various booths have been devised in an attempt to provide a paint spray booth which avoids the health hazards and provides for a control of the spraying operations. In prior booths there is an air inlet in the ceiling through which inlet very large quantities of air are conducted into the booth. This air exits from the booth through an outlet arranged in the floor or elsewhere, and the mist, fumes, paint, dust and the like are swept out of the booth by the air and are expelled simultaneously with the air. If the air inlet quantity is insufficient, it often tends to cause undesirable turbulence, and randomly directed air streams are generated which carry mist, fumes, paint, dust etc. throughout the booth. To avoid turbulence, the air is passed into the booth with a relatively high velocity. It will, however, be understood that a booth for painting, for example, car bodies has a relatively large volume. Such a booth might for example be 20-60 meters long, 5-6 meters wide and 3-5 meters high. The ventilation air will be conveyed in that at normal ambient working temperatures e.g. in the range 19.degree. to 23.degree. C. For health reasons fresh external air is normally used for the ventilation, so that in winter air at very low temperatures, for example -20.degree. C., has to be increased in temperature to a temperate condition. Therefore it will be understood that enormous amounts of energy are required to provide the necessary high volume of relatively high-velocity temperate air over the whole of the booth from ceiling to floor. Also from a practical aspect it is not possible to ventilate differentially different parts of prior booths to any significant degree without physically partitioning the booths.